Superconducting electronics that utilizes a phase difference between a plurality of superconducting components using a multi-band superconductor is disclosed in, for example, the following Documents 1 and 2 in which the inventors of the present invention, etc., are involved.
Document 1: Japanese Patent Application Laid-Open No. 2003-209301
Document 2: Japanese Patent Application Laid-Open No. 2005-085971
In the disclosed superconducting electronics, a bit which is the basic component of computing is composed using an inter-component phase difference soliton. The development of efficient soliton generation and detection method is the fundamental technology for such electronics. Note that in the case in which a propagation line is a multi-band superconductor line, the inter-component phase difference soliton is, in particular, often called an interband phase difference soliton as a narrower concept thereof, but in the present specification inter-component phase difference solitons are hereinafter generically referred to and may be simply abbreviated as “solitons”.
Meanwhile, for the generation of solitons, there are proposed a method in which a boundary condition for generating solitons is created by a magnetic field, as disclosed in the above-described Documents 1 and 2 and the following Document 3, and a method in which a nonequilibrium current is allowed to flow through a superconductor and a soliton is created together with the current, as disclosed in the following Document 4. Generation of solitons by a magnetic field is experimentally verified in the following Documents 5 and 6.
Document 3; “Soliton in Two-Band Superconductor”, Y. Tanaka, Physical Review Letters, Vol. 88, Number 1, 017002
Document 4: “Interband Phase Modes and Nonequilibrium Soliton Structures in Two-Gap Superconductors”, A. Gurevich and V. M. Vinokur, Physical Review Letters, Vol. 90, Number 4, 047004
Document 5: “Interpretation of Abnormal AC Loss Peak Based on Vortex-Molecule Model for a Multicomponent Cuprate Superconductor”, Y. Tanaka, A. Crisan, D. D. Shivagan, A. Iyo, K. Tokiwa, and T. Watanabe, Japanese Journal of Applied Physics, Vol. 46, No. 1, 2007, pp. 134-145
Document 6: “Magnetic Response of Mesoscopic Superconducting Rings with Two Order Parameters”, H. Bluhm, N. C. Koshnick, M. E. Huber, and K. A. Moler, Physical Review Letters Vol. 97, December 8, 237002
On the other hand, for the detection, there are disclosed a method for detecting generation of fractional flux created by a soliton, as disclosed in the above-described Documents 1, 2, and 3, and a method for detecting a soliton by generation of a voltage by the annihilation of a soliton-antisoliton pair or by a voltage generated when a soliton is created at a current introduction terminal, as acknowledged in the above-described Document 4. For a promising means for measuring magnetic flux smaller than unit quantum flux, there is also a detection method using a SQUID microscope such as that disclosed in the following Document 7.
Document 7: “SQUID Microscope” Toshimitsu Morooka, Kazuo Chinone, Japanese Journal of Applied Physics, Vol. 70, No. 1 (2001), pp. 50-52
When solitons are used as signal carriers (logic bits) to implement various logical operation functions, etc., control of solitons requires an external magnetic field in the conventional way of thinking. However, since a soliton does not directly interact with a magnetic field, control by an external magnetic field requires a circuit configuration therefor, which conversely causes a drawback that the circuit configuration is susceptible to an environmental magnetic field. Primarily, solitons receive attention because they have the property of not interacting with a magnetic field, which is acknowledged as an advantageous point in application to quantum computers. Thus, there is a contradiction in the conventional techniques that require the setting of a boundary condition by a magnetic field. In addition, even in an attempt to perform control of solitons by an external magnetic field, there are no techniques found to completely control solitons having high energy.
The present invention is made in view of this point, and an object of the present invention is therefore to propose a control method in which solitons can be controlled in accordance with a new control idea without the need to use an external magnetic field and thus naturally without being adversely affected by noise which an environmental magnetic field causes, and a circuit device therefor.